We present experimental homodyne tomography of an optical quantum bit represented by a single photon split into two optical modes. The reconstructed four-dimensional density matrix extends over the entire Hilbert space and thus reveals, for the first time, complete information about the dual-rail optical qubit as a state of the electromagnetic field. The experimental data violate the Bell inequ...

Avalanche Photodiodes (APDs) connected with quenching circuits can be used for single photon detection. This semiconductor photon detector has a better performance than photomultiplier. The principles and applications of APDs are presented. Features, performance of different commercial devices are introduced and compared. Recent research progress based on the improvement of quenching circuits a...

We show that it is possible in principle to realize a unit-efficiency initial state preserving interaction-free measurements (IFM) of quantum objects characterized by their superpositions. Some generalized work is also discussed. c 2001 Optical Society of America OCIS codes: (000.1600) Classical and quantum physics; (270.0270) Quantum optics The concept of Interaction free measurement (IFM) was...

Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, opt...

This paper investigates an analytical model of a system consisting of a photonic crystal waveguide, a microcavity, and a four-level electromagnetically-induced transparency atom. The transmission and reflection of the system are numerically calculated, and it shown that classical results for this class of systems can be extended to the quantum regime. In particular, these systems could enable u...

The transitional behavior of the two-photon Kerr effect between the self-Kerr and cross-Kerr cases is investigated. To this end, we have developed a semiclassical method for evaluating the two-photon Kerr effect that is applicable to any two-photon input state. It is revealed that the maximum Kerr effect is obtained when the second photon is input with a delay time that corresponds to the absor...

Photon accelerators can spectrally broaden laser pulses with high efficiency in moving electron density gradients. When driven by a conventional pulse, the group velocity walk-off experienced accelerated photons and deterioration of gradient from diffraction refraction limit extent spectral broadening. Here we show that pulse shaped space-time transverse intensity profile overcomes these limita...

The Green's function for the diffusion equation is widely used to describe photon transport in turbid media. We have performed aseries of spectroscopy experiments on a number of uniform turbid media with different optical properties (absorption coefficient in the range 0.03-0.14 cm(-1), reduced scattering coefficient in the range 5-22 cm(-1)). Our experiments have been conducted in the frequenc...